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physgopal
India
4 Posts |
 Posted - 08/16/2015 : 02:50:09 AM
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Hai, i am Gopalakrishnan. Can anyone tell about what is the equation for fitting Arrhenius plot along with its independent, dependent variables and parameter names. Also how to fit the data using this function... Thank You...
M.Gopalakrishnan |
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JacquelineHe
287 Posts |
Posted - 08/17/2015 : 06:08:31 AM
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Hi Gopalakrishnan,
If do not misunderstand you mean, you want to fit the plot by Arrhenius equation: ln(k) = ln(A) – (Ea/R) * (1/T), right?
In Origin, there is not a build –in function for it. I suggest you create a user-defined function for it.
About how to create user-defined function, please refer to this help page and tutorial:
http://www.originlab.com/doc/Origin-Help/UserDef-FitFunc
http://www.originlab.com/doc/Tutorials/UserDef-FitFunc
If in your plot “ln(k)” is in the Y axis, “T” is in the X axis
And you can define the y as dependent variables. (y is “ln(k)”), and set “T” as independent variables, and set “A, Ea” as the parameters.
And I do not confirm you can like to use the constant value for “R”.
If you set R=8.314 J/(mol*K), you can use put 8.314 in the function to instead of R.
The function body: y = ln(A) – (Ea/8.314) * (1/T)
Thanks
Jacqueline
OriginLab
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physgopal
India
4 Posts |
Posted - 08/17/2015 : 11:22:51 AM
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Dear JacquelineHe,
Thank you so much for your valuable suggestion. Actually i want to calculate the activation energy (Ea)in thermally activated processes such as low-temperature PL measurement by using this relation
I(T) = I(0)/(1+A*exp(-Ea/KT)
where (T) is the PL intensity at temperature T K, I(0) is
the PL intensity at 0 K, A is the constant describing the
capture of carriers, Ea is the activation energy of the
thermal quenching process, K is the Boltzmann
constant, and T is a thermodynamic temperature. I have create user-defined function, but when i compile the function
ITmp = I0 /( 1 + A*exp(-Ea*Tmp/(1.38*10^(-23))),
Where Tmp means T, it shows the error due to mismatching usage of parentheses. Please inform me what is the error in the above function...
Thank You so much...
M.Gopalakrishnan |
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JacquelineHe
287 Posts |
Posted - 08/18/2015 : 10:32:16 PM
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Hi Gopalakrishnan,
A right parenthesis is missed in the formula.
Please update it and try again.
Thanks
Jacqueline
OriginLab |
Edited by - JacquelineHe on 08/18/2015 10:33:30 PM |
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wells995
Taiwan
1 Posts |
Posted - 06/27/2017 : 07:45:11 AM
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Hi, I'm Wells,
I'm also looking to the same solution for this question.
I'm using OriginPro 8.1
according to the same equation which we are using here,
I'm wondering how to set up the variables?
I(T) = I(0)/(1+A*exp(-Ea/KT)
where (T) is the PL intensity at temperature T K, I(0) is the PL intensity at 0 K, A is the constant describing the capture of carriers, Ea is the activation energy of the thermal quenching process, K is the Boltzmann constant, and T is a thermodynamic temperature.
according to the formula
ITmp = I0 /( 1 + A*exp(-Ea/Tmp*(1.38*10^(-23))))
Independent Variables: Ea
Dependent Variables: I, Tmp
and then, I don't know how to setup rest to variables,
do I have to give a value of A and I0?
or I can allow fitting process do it for me?
quote:
Originally posted by JacquelineHe
Hi Gopalakrishnan,
A right parenthesis is missed in the formula.
Please update it and try again.
Thanks
Jacqueline
OriginLab
Haw Wen Chen |
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How to fit the Arrhenius plot